A video unearthed on Google Moon this week appears to show that ET may be lurking closer than we thought - and has made an underground base beneath the lunar surface.

UFO enthusiast Scott Waring was exploring the moon with the 3D software, and says, “Along the edges here there is a walled area, which tells us there is a cavity there because the wall is to keep things from falling in," Waring said.

Waring’s sighting is far from unique - his own sightings number more than 200 - and a constant stream from NASA's imagery. Perhaps the most surprising of all comes from the first man on the moon, Neil Armstrong.

“Hey, Houston, I'm looking north up toward Aristarchus now, and there's an area that is considerably more illuminated than the surrounding area. It seems to have a slight amount of fluorescence," Armstrong said.

Some believe that the glow that Armstrong saw was evidence of high technology - perhaps a fusion reactor.

Gordon Duff, a U.S. military veteran claimed that the U..S. Congress discussed the possibility of bases on the moon after the Apollo missions. Official NASA records of the period observe strange “glitter”, “mistiness” and “darkness” in the craters Man was soon to explore.

A moon base? Waring's discoveryWaring’s description seems to tally with many ideas of ‘alien’ bases on the moon - that they would be located underground, both to prootect against asteroids, and to conceal them from Earth.

"On the back side alone there is seven to eight right angles. The darkness around the edges seems to tell us that there is a large cavity underneath the structure, under the ground,” Waring says.

One of more than 200 sightings Waring claims to have made

A NASA report chronicling “unusual” sightings on the moon throughout history includes 579 entries - some stretching far back into history.

Gervase of Canterbury, writes,“About an hour after sunset on June 18, 1178 A.D., a band of five eyewitnesses watched as the upper horn of the bright, new crescent Moon ‘suddenly split in two.’ From the midpoint of this division a flaming torch sprang up, spewing out…fire, hot coals and sparks. . .The body of the Moon, which was below writhed. . .throbbed like a wounded snake.”

Others believe that images are deliberately “smudged” to conceal evidence: one UFO enthusiast writes, “Governments around the world and their organizations covering up information on Extraterrestrial life and Nasa Evidence of Alien Bases on the Moon,”

Dozens of sightings seem to include structures - or the entrances to underground bases. Many refer to “tracks” and “beacons”.

Neil Armstrong, who died in 2012, will lend his name to an operations building at Kennedy Space Centre in Florida …

Rob Shelsky and George Kempland, authors of “The Darker Side of the Moon” say. ““Someone” or “some thing” of an intelligent nature is behind most of these sightings. And, no, this answer doesn’t have to account for all of such sightings. Some small number of them could be optical illusions, meteor impacts, etc., as argued by the skeptics. Even so, because just so many events on the Moon can’t be explained satisfactorily.”

The authors claim that UFO activity seems to intensify when Earth people near the Moon - and that NASA seems keen to play down such claims.

In June of 2009, NASA launched the Lunar Reconnaissance Orbiter, a robotic spacecraft, now orbiting the Moon at an altitude of 50-200 km. LRO's primary objective is to make fundamental scientific discoveries about the Moon.

LROC is one of seven instruments on board LRO. Together, these instruments have a downlink allocation of 310 Gbits per Ka band pass and up to 4 passes per day. That translates into 155 GBytes per day of data or 56,575 GBytes per year.

Scott Waring claims to have sighted dozens of structures

“Could they have bases there now?” the authors ask. “If so, they would have to be underground nowadays, to avoid our new capabilities of detection with our lunar orbiters, and such. Underground bases are the safest way to live on the Moon. They shield the occupants from harsh solar radiation, cosmic rays, and meteorites.”

Waring’s is not the only sighting this year - with another enthusiast capturing images of what appeared to be a wedge-shaped craft hidden inside a crater.

Waring describes his find as a "pretty amazing structure" - a 'moon base'.

If aliens do live under the moon, they will have plenty of fuel, at least.

One of the Lunar Reconnaissance Orbiter's 'jobs' is to find minerals which might sustain a manned moon base: "Of particular interest is the abundance and distribution of the mineral ilmenite, an excellent source of oxygen, titanium metal, and solar-wind-implanted volatiles, such as hydrogen and helium," the team writes. "These volatile elements may facilitate the creation of water and possibly fuels."